The present invention relates generally to inking systems for printing presses. More particularly, the present invention relates to an apparatus for applying ink to an anilox roller which then applies ink to a plate cylinder of a printing press.
Many types of printing presses are well known. The present invention is especially designed for use with Flexographic or "Flexo" printing presses. However, it is understood that the present invention may be used in other printing systems. Flexo printing presses include an impression cylinder, a plate cylinder and an engraved anilox roller which is used to meter the flow of ink to a plate cylinder.
Letterpress keyless printing systems and offset keyless printing systems also include anilox rollers. However, letterpress keyless and offset keyless printing systems include additional rollers located between the anilox roller and the plate cylinder. These additional rollers transfer ink from the anilox roller to the plate cylinder. Therefore, letterpress keyless and offset keyless printing systems indirectly apply ink the plate cylinder. Water based inks cannot be practically applied with indirect inking systems. In Flexo printing systems, ink is transferred directly from the anilox roller to the plate cylinder. Therefore, Flexo printing systems can use water based inks.
Conventional Flexo printing systems include fountain type inking systems. Each anilox roller in a conventional Flexo printing system includes a pair of spaced apart reverse angle doctor blades which engage the anilox roller and define an inking chamber therebetween. An ink fountain supplies ink to the inking chamber so that a well of ink is formed between the anilox roller and the doctor blades. One doctor blade scraps off excess ink from the anilox roller while the other doctor blade holds ink in the inking chamber. Ink is applied to the anilox roller as the anilox roller rotates through the well of ink. An ink reservoir situated below the inking chamber traps run off ink and resupplies it to the inking chamber. Examples of conventional fountain type inking systems are illustrated in U.S. Pat. Nos. 2,151,968; 4,938,133; and 4,982,660.
The present invention provides an improved design over conventional fountain type inking systems normally used in modern presses. Conventional fountain type inking systems often have a number of problems. First, ink skipping may occur in fountain type inking systems. Ink skipping causes streaks in which there is no ink on the surface of the anilox roller. As the printing speed is increased, the ink skipping problem becomes more pronounced. Modern printing presses operate at very high speeds. Therefore, ink skipping has become a relatively serious problem. Ink skipping primarily results from bubbles formed in the ink as the anilox roller passes through the inking chamber at high speeds. These bubbles create air pockets that isolate the ink from the surface of the anilox roller and cause the inkless streaks on the anilox roller. This prevents the anilox roller surface from supplying ink to cover the plate cylinder. One object of the present invention is to reduce the problem of ink skipping.
Another problem associated with fountain type inking systems is that leakage may occur at end seals of the fountain. The doctor blades and various other components of fountain type inking systems may also leak. Leakage may cause a build up of ink on the impression roller and the plate cylinder.
Yet another problem associated with fountain-type inking systems is that the doctor blade is difficult to change. This results in lengthy printing press down times when it is necessary to change the doctor blade. One object of the present invention is to provide a reversible doctor blade assembly which facilitates changing of the doctor blade and reduces press down time.
Fountain type inking systems also tend to splash or throw off ink as the anilox roller moves through the fountain. Such ink spillage problems have made it necessary to provide a complex system of seals around a major portion of the anilox roller in fountain type inking systems. Even with the most effective seals, however, some leakage is typically present. Ink leakage may result in damage to the printed product from ink that leaks onto the paper web. In addition, the ink leakage problem makes cleaning the press more costly, both in terms of manpower requirements and press down time. The inking apparatus of the present invention is designed to reduce the abovementioned problems.
Another object of the present invention is to provide an ink fountain for applying ink to the anilox roller without substantial leakage and which can be cleaned easily.
According to one aspect of the present invention, an inking apparatus is provided for applying ink to a rotating roller of a printing press. The apparatus includes an elongated ink manifold located adjacent the roller, and a plurality of spray nozzles coupled to the manifold. The plurality of spray nozzles are spaced along the manifold for spraying ink onto the roller. The apparatus also includes a wiper for engaging the roller to remove excess ink from the roller. The wiper is located adjacent the roller and is spaced apart from the manifold. The apparatus further includes a spray chamber surrounding the manifold and wiper for containing excess ink therein.
The apparatus further includes an ink supply, a water supply, and a valve coupled to the ink supply, the water supply, and to the manifold. The valve controls the supply of ink and water to the manifold. The valve selectively supplies ink, water, or a mixture of ink and water to the manifold.
An illustrated embodiment of the inking apparatus is used in a printing press system which includes an impression cylinder, a plate cylinder, and an anilox roller for supplying ink to the plate cylinder upon rotation of the anilox roller and plate cylinder. The inking apparatus includes an ink sprayer located adjacent the anilox roller for spraying ink onto the anilox roller, and a wiper located adjacent the anilox roller and spaced apart from the ink sprayer. The wiper engages the anilox roller to remove excess ink from the anilox roller as the anilox roller rotates. The apparatus also includes a spray chamber surrounding the ink sprayer and wiper for containing excess ink therein.
The present invention improves and simplifies printing on a Flexographic or other types of printing presses. Ink, water, or a mixture of ink and water coming from separate supply lines flows through the ink and water control valve. The supply lines are coupled to check valves to permit a programmable controller on the press to supply ink, water, or a mixture of ink and water to the spray manifold.
The angle of alignment between the plurality of spray nozzles and the roller is preferably adjustable. The spray manifold is movable over a range of at least 90.degree. so that the manifold can accommodate different press designs and printing needs. The rate of fluid flow from spray nozzles coupled to the spray manifold can also be adjusted for metering the amount of ink applied to the anilox roller.
The wiper for removing excess ink from the anilox roller is also adjustable over a range of angles of at least 180.degree.. This provides control over inking of the anilox roller and both forward and reverse couples. A press operator can select an appropriate angle for the wiper to best suit the operator's printing needs.
The present invention is designed to increase the useful life of an anilox roller. In addition, ink cost is reduced because the spray nozzles can be adjusted to deliver only the amount of ink needed. Using the inking apparatus of the present invention, a press can run longer and have less chance of extended down time without maintenance. The inking system and wiper designs of the present invention reduce waste, decrease clean-up time, lower labor cost, and lessen the extra cost associated with extensive waste water treatment systems that may be required with conventional inking systems.
According to another aspect of the invention, an inking apparatus for applying ink to a rotating roller of a printing press. The apparatus includes an ink fountain located adjacent the roller for applying ink to the roller, a doctor blade holder, and a doctor blade coupled to the doctor blade holder for engaging the roller with a predetermined pressure to scrape excess ink from the roller as the roller rotates relative to the doctor blade. The apparatus also includes first and second guide rails configured to define a slot therebetween for receiving the doctor blade holder therein, and means for retaining the doctor blade holder in the slot to hold the doctor blade against the roller during rotation of the roller.
The ink fountain includes an angle iron located adjacent the roller to define an ink reservoir therebetween and an elongated supply pipe located in the ink reservoir for supplying ink to the ink reservoir. The apparatus further includes an ink supply, a water supply, and a valve coupled to the ink supply, the water supply, and to the supply pipe. The valve selectively controls the supply of ink, water, or a mixture of ink and water to the supply pipe. Preferably, the valve is coupled to the supply pipe at a location near a midpoint of the supply pipe.
The elongated supply pipe is formed to include a plurality of elongated slots therein for discharging ink from the supply pipe into the ink reservoir. The plurality of elongated slots are spaced apart along a longitudinal axis of the supply pipe.
The retaining means includes a mounting plate coupled to the second guide rail for covering the slot to retain the doctor blade holder in the slot. The retaining means also includes means for engaging the doctor blade holder to hold the doctor blade against the roller during vibration of the printing press.
Other objects, advantages, and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.